In this series we are exploring NASA’s top five challenges as detailed in its Civil Space Shortfall Ranking, which is basically NASA’s Christmas wish list. These are the technologies that NASA believes we need to develop if we want to go to space…and stay there.
That brings us to the number 3 highest-priority technology for long-term space activities: better computers.
Computers have been involved in spaceflight since almost the very beginning. Just like on the Earth, computers aid in a variety of tasks, like navigation and communication. But unfortunately, space is really, really unkind to electronics.
It’s not so much the vacuum of space; a circuit board does just fine. And freezing cold temperatures aren’t that big of an issue either. No, it’s our old friends, the cosmic rays. Each cosmic ray consists of a single proton or atomic nuclei, and the most powerful ones have the energy equivalent to a thrown baseball – which doesn’t sound like much, but when you cram that baseball down to the size of a subatomic particle, it can be rather nasty.
Most cosmic rays slip through tissues and computer circuitry with ease; they’re so small they literally miss the atoms and molecules of larger objects. But every once in a while they can strike, delivering all their energy to whatever they encounter. In humans, this can lead to an increased risk of cancer. In computers, it can lead to fatal glitches.
In 2022 the Voyager 1 spacecraft, launched all the way back in 1977 and is currently sailing beyond the borders of our solar system, started sending back garbled transmissions. By this point, voyager had spent decades cruising the outer solar system, giving us the most pristine images of the giant planets and our first taste of interstellar space. Most of the spacecraft was operating normally, but not the attitude articulation and control system, which is responsible for keeping Voyager’s radio antenna pointed back to Earth, was just creating nonsense. Engineers were able to fix the issue by uploading the equivalent of a software update to route around the malfunctioning circuitry, although they never discovered the root cause of the problem. Many suspect that a cosmic ray struck a piece of circuitry at just the wrong moment to cause the problem.
More sophisticated computers are vulnerable as well. In 2023 the James Webb Space Telescope, the largest and most advanced telescope ever sent into space, suffered a minor malfunction when it’s Near infrared Imager and Slitless Spectrograph, or Niriss, an important scientific instrument used to study exoplanets, become unsynchronized with the rest of the spacecraft, rendering it useless. NASA engineers suspected a cosmic ray led to the malfunction, but thankfully they were able to restore order by, essentially, turning it off and turning it back on again.
These issues were easy to solve, but it’s only a matter of time before a cosmic ray strikes at a critical moment, shutting down a much more important mission. To protect against the ever-present threat of cosmic rays, spacecraft engineers take years to develop onboard computers and ensure that they are hardened against radiation. It’s for this reason that computers going into space tend to be a couple…or more…generations behind the curve.
In 1969, the Apollo 11 mission’s guidance computer weighed 70 pounds and was capable of performing about 40,000 instructions per second, which is over 100,000 times slower than the smartphone you’re probably using right now. The International Space Station featured several custom-build computers with took nearly a decade to develop.
If we’re going to maintain a larger presence in space, this isn’t going to cut it. We need advanced hardware to handle a variety of complex tasks: more sophisticated navigation and tracking, much larger data communication loads, assistance with scientific surveys and studies, and more. Plus, we need our computers to be more fault tolerant, so that a stray cosmic ray doesn’t derail an entire mission, and we need to be able to easily swap out computing modules when they go space crazy on us, because we need maximum adaptability to achieve our long-term plans.
Ironically, one of our biggest challenges with sending more powerful computers into space is how to deal with the heat. Yes, away from the Sun, space is cold, just a few degrees above absolute zero. But it’s also a vacuum, which means there’s no air or water to easily transport away heat. It’s not just you can just plop a fan on the side of the CPU. So heat can easily build up to dangerous – for delicate circuitry – levels. Plus, shielding against cosmic rays isn’t as simple as putting up a wall. That’s because cosmic rays can strike the molecules in the wall itself and send out a shower of still-energetic particles that can disrupt circuitry.
We’ll have to come up with many clever solutions if we want our space-based computers to be as fast and reliable as our Earthbound ones.
